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Science  30 Oct 2009:
Vol. 326, Issue 5953, pp. 680
DOI: 10.1126/science.326_680

30 October 2009

Edited by Edward W. Lempinen

Barnard Lecture

As Climate Change Intensifies, McCarthy Urges Adaptation Focus

James J. McCarthy

Scientific assessments of climate change have evolved dramatically over the past three decades, amassing evidence to persuade the world that warming is real and that humans are the primary cause. But greenhouse gas concentrations have continued to soar, and influential climate expert James J. McCarthy says future assessments must focus on how humanity can best adapt.

At the 10th AAAS Robert C. Barnard Environmental Lecture, McCarthy said climate change is already fueling drought and other extreme events that are most keenly felt on a regional scale. The longer emissions remain unchecked, he warned, “the harder adaptation will be, particularly for those parts of the world that are unprepared” for these extreme events.

Strategies such as switching to crops better suited to warmer growing conditions and relocating businesses from areas vulnerable to sea-level rise should be considered immediately, according to a June report by the United States Global Change Research Program. McCarthy, chairman of the AAAS Board, was a member of the report's 31-author team.

“We may reach a point,” McCarthy said, “where we're going to be so desperate that we will need to look critically at various geoengineering approaches” such as burying CO2 in abandoned oil fields and seeding the atmosphere with fine particles to reflect some sunlight back to space.

The annual Barnard Lecture is endowed by the international law firm of Cleary, Gottlieb, Steen & Hamilton to honor Barnard, the late counsel to the firm, for his contributions to environmental and public health law.

Extreme threat. Researchers say continuing climate change could make severe events such as the August 2009 Station Fire in Southern California more prevalent.

[Courtesy of Brent Buffington, JPL]

McCarthy is the Alexander Agassiz Professor of Biological Oceanography at Harvard University. He has served on several global and regional assessment panels, and he used his talk to trace the evolution of assessments from the 1970s to the upcoming climate summit in Copenhagen. Thousands of scientists worldwide, working under the Intergovernmental Panel on Climate Change (IPCC), issued critical reports in 1990, 1995, 2001, and 2007 that helped move governments to action on climate change, said McCarthy, who was co-chair of a working group for the 2001 report.

But because past goals for greenhouse gas stabilization established by United Nations treaties in Rio de Janeiro and Kyoto have not blunted emissions, “we are headed to dangerous territory at breakneck speed,” he warned.

Climate change has been established as unequivocal, McCarthy said, but the next report must assess more directly the regional impacts of climate change and how to cope with them. The most recent IPCC report identified such impacts on every continent. “In every nation,” he cautioned, “there will be people who will be vulnerable.”

Along with his work on the June report “Global Climate Impacts in the United States,” McCarthy was a lead author on the Arctic Climate Impact Assessment in 2004—2005. These regional snapshots, he said, may help politicians and their constituents to grasp the immediate stakes of climate change.

“In different regions they make projections, so that people who have been wondering what's happening with their water or what's happening with their winters or their summers can see that they are consistent with the projections that come from our climate

models,” he explained.

The U.S. report also underscores the importance of reducing greenhouse emissions and producing and using energy more efficiently. Nations could begin serious mitigation today without further research, McCarthy said. “What is lacking is resolve.”

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